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I was servicing a Dunham-Bush 10 ton chiller at a downtown bank building, last Friday... Went on the roof to check the condenser. The HVAC sytem has been there for 50 years, I would guess. The condenser had been painted, coated, several times over the years. This tag was ready to fall off, so I helped it. Cleaned off all the paint and crud... Here it is.....

First of all, isn't it cool!!! Beautiful pressed aluminum that has lasted for 50 years! How many 10 year old units do you service, the mod & s/n are gone.

There must be internal aluminum fins to help heat transfer, and methyl chloride would have reacted with them.

D/B Inner Fin.........

I may be a little rusty on my history, so please bear with me. Dunham-Bush was formed over a short period of time in the 50's by Cecil Boling, Red Mulcahey (and others) from many different existing companies. C.B.Dunham was in the steam heating business, Bush Mfg was originally makers of auto radiators, Brunner which made compressors and Heat-X which made heat exchangers like water-cooled condensers and DX chillers.

One of the patents that was held by Heat-X, and therefore D/B, was the inner-fin deal which was an early forerunner of todays turbulators and other "enhanced" heat exchangers tubing surfaces. The inner-fin was an inserted aluminum spiral fin to increase the turbulence and thus the heat transfer on the refrigerant side of chillers and other heat exchangers.

I like running across nostalgic pieces like this, too. I was working in a meat market in FT Pierce, FL a few years back.......It had been a Piggly Wiggly supermarket back in the forties or fifties. Way up in the overhead in the back room was an ancient 20-ton air handler (the old compressor base was still in the motor room) long abandoned with a brass plate that read "FRIGIDAIRE-Division of General Motors". I should have snatched it up when I had the opportunity.

1949

In the 1970's, the condensing unit was replaced by a Carrier with an 06D.

Last breakdown was 1998, when I had to replace the original condenser fan motor.

I'll have to check on whether or not it's an inner fin, but I don't think it is. I do know that it was originally R12, but was changed to 22 with the new unit. I have no evidence to indicate that the refrigerant charge is not original, also.

The B&G 100 perched precariously above it is NOT original, neither is the freezestat to the upper left, nor is the actual temp control, upper right. The outdoor reset relay is, AFAIK, as old as or older than I.